vin082 COBOL Patterns Reference
Anti-Patterns (Flag During Parsing)
CRITICAL Risk — Flag immediately
| Pattern | Identifier | Risk |
|---|---|---|
| ALTER verb | ALTER para-name TO PROCEED TO other-para |
Self-modifying code — no automated migration path |
| GOTO with complex control flow | Multiple GOTOs across sections | Spaghetti control flow |
| REDEFINES on large groups | REDEFINES on 01-level items | Memory overlap — maps to complex union types |
HIGH Risk
| Pattern | Identifier | Risk |
|---|---|---|
| Deep PERFORM THRU | PERFORM A THRU Z spanning many paragraphs |
Implicit flow coupling |
| Numeric GOTO (COMPUTED GO TO) | GO TO para1 para2 DEPENDING ON var |
Switch via GOTO — complex to map |
| OCCURS DEPENDING ON | OCCURS 1 TO 100 DEPENDING ON counter |
Dynamic arrays — need careful Java handling |
| Global working storage mutation | Paragraphs modifying 01-level items with no encapsulation | Hidden state — risk in concurrent Java |
MEDIUM Risk
| Pattern | Identifier | Risk |
|---|---|---|
| Implicit string padding | MOVE short-string TO long-string (COBOL pads with spaces) | Java Strings don't pad — behaviour change |
| Numeric truncation | MOVE large-pic TO small-pic | Java throws; COBOL truncates silently |
| INSPECT/STRING/UNSTRING | String manipulation verbs | Complex but mappable to String methods |
| Timezone-unaware date arithmetic | DATE-OF-INTEGER, INTEGER-OF-DATE without timezone | Careful Java LocalDate mapping needed |
Modernization Signals (Positive Indicators)
Easy Migration Signals
- Single entry/exit paragraph structure (0000-MAIN → sub-paragraphs)
- No GOTO, no ALTER
- LINKAGE SECTION matches clean service interface
- Pure computational programs (no file I/O, no CICS)
- Small line count (<300 lines) with low coupling
Batch Job Signals (→ Spring Batch)
- OPEN INPUT ... OPEN OUTPUT patterns
- PERFORM UNTIL EOF loops
- READ ... AT END patterns
- No LINKAGE SECTION (no external callers)
Service/API Signals (→ Spring @Service or @RestController)
- Has LINKAGE SECTION parameters
- Called by many programs (high fan-in)
- No direct file I/O (delegates to other programs)
CICS Transaction Signals (→ REST API or Spring MVC)
- EXEC CICS SEND/RECEIVE MAP
- EXEC CICS RETURN TRANSID
- EXEC CICS READ/WRITE